Photoshop posterization problem

Decu, The posterization has 19 perfect concentric circles from 236 to 256 with each concentric ring incremented by a value of 1 over the previous ring.. The first thought that comes to mind is that someone applied a radial gradient to a layer and then did Image>Adjust>Posterize with a value of 19. However, there could also have been many other ways that could have caused this effect. To know exactly what caused it would probably require more detail of the workflow and what was done to the image.
For those who can not see the effect, you probably need to recalibrate your Monitors or perhaps you are using LCD monitors that can not be calibrated in that range.
Regards, Murray

Other things that come to mind are combination of camera lense and jpg processing by the camera. It could also be a bad / low quality scanner. But again there may be many other explanations. So more info would be useful.
Regards, Murray

Didn't find so much info about your monitor, but it's a $1500 monitor. All monitors below $3000 are not professional monitors and tends to show no more than 256 tonal values per channel, meaning that these monitors are not able to show a full range of tonal values above 256 per color or gray scales. Also, all these monitors are just 8 bits of depth and also below the sRGB gamut and also, all these technical stuff represented by 72 pixels per inch, so we can say we just see quite less than a 25% of the total information held by any digital image.

These are professional monitors 16 bits made (for color and gray scale images) with a gamut a bit over Adobe RGB 1998 and they cost an eye of the face: http://www.eizo.com/global/ but still 72 PPI.

Decu, The posterization has 19 perfect concentric circles from 236 to 256 with each concentric ring incremented by a value of 1 over the previous ring.. The first thought that comes to mind is that someone applied a radial gradient to a layer and then did Image>Adjust>Posterize with a value of 19. However, there could also have been many other ways that could have caused this effect. To know exactly what caused it would probably require more detail of the workflow and what was done to the image.
For those who can not see the effect, you probably need to recalibrate your Monitors or perhaps you are using LCD monitors that can not be calibrated in that range.
Regards, Murray

Murray
I didn't do anything with the image, its just a white background with 19% gray brush point. Try to do this on your PC, is the result the same?